Luminous gas discharge device



Oct. 9, 1956 K. SCHUMICHEN LUMINOUS GAS DISCHARGE DEVICE Filed March 15, 1955 INVJfJ NTOR. KARL. SEHUMIEHEN United States PatentO 2,7ss,39s

LUMINOUS GAS DISCHARGE DEVICE Karl Schiimichen, Wiesbaden, Germany, assignor to Physikalisch-Technische Werksttitten Application March 1955, Serial No. 494,378 Claims priority, application Germany March 19, 1954 4 Claims. (Cl. 313-117) This invention relates to luminous gas discharge devices in which a gas discharge is produced between two electrodes and particularly relates to such devices in which a discharge concentrated in space is produced. Such devices are used, for example, in high speed photography.

In devices of this type, the space discharge is concentrated or narrowed down in the direction of one axis of the envelope, and a window is provided on the envelope in such a position that light emanates from the tube in the direction of the envelope axis.

The useful life of devices of this type is considerably shortened by the fact that the light transparent window of the envelope becomes blackened after a relatively short time. This blackening is caused by the bombardment of the inner surface of the window by minute particles which are separated from the cathode during the gas discharge. blackening. In conventional flash bulbs in which the entire discharge gap serves as a light source, this is generally achieved by screening of the cathode. In lamps designed to give a more or less point source of light, it has been attempted to prevent blackening by special treatment of the cathode material, by the use of high quality gas, and by the use of particularly suitable getter material. By these means the blackening effect is reduced but cannot be completely avoided.

It is an object, therefore, of the present invention to provide an improved luminous gas discharge device, in which blackening of the light window is substantially prevented.

In accordance with the present invention there is provided a luminous gas discharge device comprising a first envelope portion having a light transparent window, and a first electrode located in this envelope portion. A second envelope portion joined to the first portion by a relatively narrow envelope neck portion, is also provided with a hollow member extending into the neck portion. A second electrode extends into the hollow member, and the second envelope portion is designed to have a larger volume than the first envelope portion.

For a better understanding of the invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the accompanying drawing, the single figure illustrates a luminous discharge device in accordance with the invention, comprising envelope portions 1 and 2, the latter having a light transparent window 3, while the remainder of the interior of the envelope, preferably made of glass, is silver or nickel plated as indicated by the shading in the drawing. Envelope portions 1 and 2 are joined by a relatively narrow neck portion 8. The envelope portion 2 contains a circular anode 7, while a cathode 6 extends along the axes of the two envelope portions, as shown, and is sealed in through the bottom of envelope portion 1.

For the purpose of concentrating the gas discharge in Various means have been tried to prevent this a relatively small space, there is provided a hollow member 4, extending through neck portion 8, to the edge of the'space inside envelope portion 2, and fused to a quartz tube 5, as shown, which in turn is fused to envelope portion 1. Because of the high temperatures produced during a gas discharge, the hollow member 4 is also preferably made of quartz or hard glass.

The volume of envelope portion 1 is made to be larger than that of envelope portion 2, and can further effectively be enlarged by providing-a number of openings, not shown, in the tube 5, preferably-near its point of fusion with invelope portion 1.

The operation and the advantages of this novel design are based on the theory that sudden ionization of the entiredischargegap occurs at the instant of a gas discharge. This discharge is in the manner of a gas explosion, producing a considerable pressure. In accordance with this invention, the envelope of this device is so designed that this pressure occurring during the discharge is relieved in a direction opposite from the direction of the light emanating from the device.

Reduction of blackening of the window is now achieved by the following design features:

1. The envelope portion of the device which has the light transparent window, and the anode, in the present case, anode 7, must have a smaller volume than a second envelope portion, in this case, portion I, joined to the other portion by means of a relatively narrow neck portion 8.

2. For thermal reasons the discharge must take place in a quartz or hard glass tube, and the free end of this tube must extend to the periphery of the smaller space or envelope portion provided with the light transparent window.

3. The cathode, in this case, cathode 6, introduced through the larger envelope portion 1, must extend close to the opening or the end of the discharge tube or hollow member 8.

In the above arrangement, electrodes 6 and 7 can readily be interchanged, so that 7 becomes the cathode, and 6 the anode, without changing the operation or performance of this device. In a device in which the above three features are incorporated, the discharge energy is produced in the small envelope portion 2, which is provided with the light transparent window 3. The pressure produced therein immediately causes a flow of gas into the larger space of envelope portion 1, and this fiow carries with it all impurities in the gas, that is, also the minute particles of material loosened from the cathode at the time of the discharge. These particles are then deposited on the walls of envelope 1 where they cannot impair the light transmission through window 3.

Hence, by producing a flow of gas away from the light transparent window, electrode particles are carried with the gas stream away from the window and, therefore, are not deposited on the window and do not impair the light transmission therethrough.

While there has been described what is at present considered to be the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A luminous gas discharge device comprising a first envelope portion having a light-transparent window, a first electrode located in said first envelope portion, a second envelope portion, a relatively narrow envelope neck portion joining said first and said second envelope portions, a hollow member extending into said neck portion, a second electrode extending into said hollow member, said second envelope portion having a larger volume than said first envelope portion.

2. A luminous gas discharge device comprising a first envelope portion having a light-transparent window, a first electrode located in said first envelope portion, a second envelope portion, a relatively narrow envelope neck portion joining said first and said second envelope portions, a hollow member extending through said neck portion into said first envelope portion, a second electrode extending into said hollow member, said second envelope portion having a larger volume than said first envelope portion.

3. A luminous gas discharge device comprising a first envelope portion having a light-transparent window, a first electrode located in said first envelope portion, a second envelope portion, a relatively narrow envelope neck portion joining said first and said second envelope portions, a hollow member extending through said neck portion into said first envelope portion, a second electrode extending into said hollow member sufiiciently close to the end of said last-named member so as first to permit discharge energy to be liberated in said first envelope portion, said second envelope portion having a larger volume than said first envelope portion.

4. A luminous gas discharge device comprising a discharge space suited to envelope a gaseous discharge, a light-transparent window bounding at least a portion of said space, a second space joined to said first space by a relatively narrow connecting space, said second space having a larger volume than said first space, a first electrode located in said first-named space, a second electrode extending into said connecting space in the direction of said first electrode so as first to permit discharge energy to be liberated in said first-named space.

References Cited in the file of this patent UNITED STATES PATENTS Knowles Aug. 11, 1936 

